Natural energy is abundantly available throughout the world in various forms such as natural wind, solar, tidal and wave energy. Heretofore, it has not been feasible to utilize large quantities of natural energy in the production of electricity having an alternating current except in somewhat specific circumstances. For example, windmills have been used for the production of electricity although such use has typically been limited to the production of small amounts of electricity. Water energy including both tidal and wave energy has been used in the production of electricity but once again such use has not been shown to be economically feasible on a large scale. Finally, electricity has been produced directly from natural solar energy although once again such a production of electricity is not yet economically feasible on a grand scale.
Conventional sources of energy for the production of electricity such as oil, gas, coal and wood are in an ever dwindling supply which necessitates that natural forms of energy be utilized to a greater extent. The natural forms of energy are effectively inexhaustable and are typically available in one form or another throughout the world.
Unfortunately, both the average and peak demands for electrical energy in homes and in industry are typically out of phase with the availability of natural sources of energy. For example, tidal and wave action, although somewhat predictable does not oftentimes coincide with the times at which peak electrical energy is required. Similarly, solar energy is most abundant typically during the middle of the day with the peak demand for electrical energy, however, oftentimes occuring later in the evening and gradually decreasing thereafter. Accordingly, it is necessary that the natural energy be somehow stored so as to be releasable during those periods of average and peak demand as required.
Perhaps the most common method of storing electrical energy is with batteries. Large storage batteries have been developed on a commercial basis and have been used both on farms and in industry. Electrical storage batteries, however, are objectionable due to problems relating to maintenance and reliability. Furthermore, electrical storage batteries are limited to providing electrical energy having a direct current. Such DC electricity is not compatable with the vast majority of conventional appliances and motors. Accordingly, a need exists for a dependable and economical method and apparatus for storing natural energy, preferably in a manner by which the natural energy can be converted to AC electricity.
Various systems are known for utilizing natural energy to produce energy in a usable form such as for example electrical energy or mechanical energy. Furthermore, an arrangement is known wherein wind, water movement and/or sunlight are used to drive hydraulic pumps for the pressurization of a hydraulic fluid. In the arrangement, the hydraulic fluid is supplied to a cylindrical tank having a weighted piston. The hydraulic fluid is withdrawn from the tank by way of a pressure and flow regulator to drive a hydraulic motor. Such an arrangement is described in U.S. Pat. No. 4,031,702 issued to Burnett et al on June 28, 1977.
Natural energy conversion systems such as are disclosed in the Burnett et al patent have objectionable characteristics and limitations, however, resulting particularly from the use of a weighted piston storage tank. Weighted piston storage tank systems are somewhat impractical because the weighted piston must be very heavy and bulky in order to provide the necessary pressurization. Furthermore, the use of weighted pistons requires that the storage tank be oriented in a generally vertical manner. The vertical orientation is necessary in order to make use of the force of gravity on the weighted piston.
Another system for converting one form of natural energy into usable electricity utilizes an elevated reservoir for the storage of excess energy and is disclosed in U.S. Pat. No. 4,010,614 issued to Arthur on Mar. 8, 1977. In the system of the Arthur patent, a solar collector produces steam to drive an electrical generator and a hydraulic pump. When the demand for electrical energy is below the capacity of the generator, the excess energy is used to drive the hydraulic pump. Water is transported by the hydraulic pump from a low level reservoir to the elevated reservoir to thereby store potential energy. When demand has increased beyond the capacity of the generator or when the supply of solar energy is decreased sufficiently, water from the elevated reservoir is used to drive a second electrical generator.
The system of the Arthur patent, however, is not readily usable in many situations since an elevated reservoir for storing water is necessary. In order to drive an electrical generator of a commercial capacity, the elevated reservoir for water must have a particular minimum elevation and must furthermore have a storage capacity of a rather large amount.
The present invention overcomes these and other problems of the prior art in that the natural energy conversion system utilizes a plurality of natural energy sources for the pressurization of hydraulic fluid. A plurality of natural energy sources are used so that periodic and intermittent fluctuations in the supply of natural energy of one particular form may be compensated for by the other forms of natural energy. The pressurized hydraulic fluid is supplied to at least one high pressure storage tank wherein a compressible fluid is compressed by the pressurized hydraulic fluid. Electrical energy is produced by the pressurized hydraulic fluid and is supplied as needed to various consumers. Excess electricity which is not needed by consumers is supplied to an electric motor which drives a hydraulic pump. The excess energy is thereby utilized to pressurize hydraulic fluid which is supplied to the high pressure storage tanks. In this way, excess energy is conserved and is not wasted needlessly.
Accordingly, it is an object of the present invention to provide a natural energy conversion system utilizing various forms of natural energy for the production of electricity.
Another object of the present invention is to provide a system for the production of alternating current electricity by a utilization of various forms of natural energy to pressurize a hydraulic fluid.
Still another object of the present invention is to provide a system for the utilization of natural energy for the production of AC electricity wherein the natural energy is utilized to pressurize a hydraulic fluid that is stored in a pressurized storage tank by compressing a compressible fluid.
The apparatus of the present invention includes a plurality of devices for converting natural energy such as natural wind, solar, wave and tide energy to pressurize a hydraulic fluid. The hydraulic fluid is supplied to the various devices from a supply tank which is preferably at a low pressure, for example, atmospheric pressure. The pressurized hydraulic fluid is supplied to one or more high pressure storage tanks through a hydraulic energy junction. The high pressure storage tanks supply pressurized fluid preferably at a substantially constant rate to a hydraulic motor which drives an electrical generator. Electricity having an alternating current is generated and is supplied as needed to various consumers including both homes and commercial utility companies. Excess electrical energy is supplied to an AC electrical motor which in turn drives a hydraulic pump. The hydraulic pump pressurizes hydraulic fluid from the low pressure storage tank and supplies the pressurized hydraulic fluid to the high pressure storage tanks. In this way, excess electrical energy is conserved and is utilized to pressurize hydraulic fluid for later use in the production of electricity.
The high pressure storage tanks may be of various configurations with a compressible fluid such as air or nitrogen being compressed by the pressurized hydraulic fluid. If the storage tanks are arranged vertically, the tanks may be provided with a piston to separate the compressible fluid from the hydraulic fluid. If the storage tanks are to have a large capacity, for example, for the production of electricity on a commercial scale, it may be advantageous to arrange the storage tanks horizontally in an underground facility. In such a facility, the storage tanks would preferably be encased in high strength concrete.